The first commercial flights from Beijing's new Daxing International airport took off on Wednesday - an airport that cost US$63 billion to build, is roughly the size of 100 football fields and is expected to become one of the world's busiest.

Shaped like a phoenix - though to some observers it is more reminiscent of a starfish - the airport was designed by famed Iraqi-born architect Zaha Hadid. It boasts four runways and is expected to handle up to 72 million passengers a year by 2025, eventually reaching 100 million.

It was hailed as "a new powerful source of national development" at a ceremony overseen by President Xi Jinping, just days ahead of the 70th anniversary of the founding of the People's Republic of China.

A China Southern Airlines Airbus A380 flight to Guangzhou in the country's south was the first to fly out.

China is forecast to overtake the United States as the world's largest aviation market by 2022. Daxing, located south of Beijing, will help ease pressure on Capital International Airport in the city's northeast, where capacity constraints often cause flight delays.

The new airport is, however, about 46 km (29 miles) away from central Beijing, almost twice the distance of Capital airport. An express train from Daxing will take about 20 minutes to reach the south of Beijing.

Daxing will also accommodate passengers from the neighboring areas of Hebei and Tianjin, linked by a sprawling network of trains, subways and public buses.

China Southern Airlines and China Eastern Airlines will be the main domestic carriers at Daxing. About 50 foreign airlines, including British Airways and Finnair, plan to move all or part of their operations in the next few quarters.

The relocation of all airlines is to due to be completed by the winter of 2021.

With the opening of Daxing, Beijing Nanyuan Airport, China's oldest airport, will cease operations from Thursday.